Automatic clutches are increasingly being used in vehicles lately not just for comfort reasons but also to cut down on wear of the components. Actuation devices of such automatic clutches frequently contain an incremental sensor that automatically detects the travel of an actuation member of the clutch or the rotation of an actuator, such as an electric motor. For a precise control or regulation of the clutch actuation, it is necessary to know the exact position of the actuation member because the clutch in most cases is driven in such a manner that it is able to transmit a prescribed torque that is a function of the position of the actuation member. This clutch torque is saved in an electronic memory as a characteristic curve that is a function of the position of the actuation member. It is therefore necessary to compensate or reference the signal of the incremental sensor periodically, i.e., to adjust the actuation member to a set point or reference value to which the count of the incremental sensor may then be referred. This referencing normally occurs at a limit stop. In German Patent Application 199 53 292 A1, a method is described in which, as a function of various input signals, a decision is made about whether the referencing of the incremental travel measurement is to occur with the clutch engaged or disengaged.
The referencing of a clutch actuator at a limit stop assumes that, depending on the configuration of the clutch actuation, which may be accomplished in various ways, the clutch may either be fully engaged or fully disengaged. This complete engagement or disengagement of the clutch is only possible in certain situations, so time delays between request and the execution of a referencing cycle are inevitable.